General Motors was a big user of Motorola 68k variants. Workstations and personal computers that used the 680x0 series switched to the Power series, maybe the developers just find them easier to migrate to.

The ISA is not better than others in any real way, but IBM put a lot of early work into RAS features for their server chipsets, and this sort of leaked into the automotive and aviation world.

If you want to run 3 cpus lockstep, verifying each other's results, the PPC world already has the infrastructure. This and other similar things make it an easy choice for some applications.